Digital image processing has become a significant form of image processing because of continuing improvements in techniques and increasingly powerful hardware devices. Digital image processing techniques have augmented and, in some instances, replaced methods used by photographers in image composition and dark room processing. For example, digital image processing techniques such as contrast balancing, edge sharpening, color balancing, or retouching of distortions are employed for editing original photographic images. Moreover, with the aid of a computer, digitized images can be edited to achieve a variety of effects such as changing the shapes and colors of objects and forming composite images.
In particular, digital image processing techniques are utilized to remove distortions from photographic images which often arise when photographs in a physical format, such as films or prints, deteriorate through use and age. An especially common form of deterioration occurs when the photographs are scratched, folded, or torn. These forms of deterioration typically cause relatively narrow, elongated regions of distortion in the image where the original image information has been lost.
A common technique for removing such distortions employs digital painting to subjectively cover or replacement the area of image distortion with a corrected image in much the same manner as an artist paints a canvas. While this technique works for its intended purpose, it is seen as relatively impractical for persons unskilled in digital painting and may require them to use specialized input devices to reduce errors.
While, the progress of integrated circuit technology in recent years has made it feasible to implement advanced graphic editing techniques in a computing environment at a lower relative cost which may be used to, among other things, remove image distortions, these graphic editing techniques continue to remain relatively complex or provide results which introduce distortions into the overall image. For example, one current imaging application sold under the brand name "ADOBE PHOTOSHOP" offers a correction tool which applies a median filter over the complete image for the purpose of removing a distortion through the blurring thereof to the point where it is no longer noticeable. Unfortunately, this process also tends to blur the details of the remaining portions of the digitized image causing a degradation in overall image quality.
Another approach requires the user to utilize a cursor to delineate the area of distortion, after which pixels from areas surrounding the distortion are utilized to replacement in lost image information. This approach is believed to be used in the imaging application sold under the brand name "KAI'S PHOTO SOAP" by Metatools Inc. While this approach provides an image having an overall better quality relative to the technique discussed previously, the amount of manual dexterity needed to specify the region of distortion renders the technique relatively complex to use.
In light of the foregoing, a need exists for a method and apparatus for removing narrow, elongated distortions from a digital image without requiring technical skill, artistic ability, or manual dexterity on the part of the user. Such a system would allow an unskilled user to remove those types of distortions from a photograph while maintaining overall image quality without requiring undue expense or the assistance of a specialist.